This invention is a technique for providing isolation between the two channels of a handsfree telephone subset without resorting to gain switching or gain variations in the transmission path. The invention involves separating the frequency spectrum into two portions and allowing the stronger signal to capture a major portion of that available spectrum. Switched capacitor filters are used to control the degree of frequency bandwidth allocated to each channel while the filters are clocked from a c...

A method of increasing the terminal coupling loss in a digital half-duplex handsfree terminal is provided. When the terminal receive channel is active an idle code which is effectively zero is transmitted by an idle code generator. When the terminal transmit channel is active a normal speech signal is transmitted. To determine which channel is active, a receive speech signal level is measured at the receive channel input, and a "virtual" transmit speech signal is computed from a signal in the tr...

The invention provides an audio subsystem for use in a telephone terminal operable in handsfree mode and comprises a receive path including a receive transducer for generating audio signals from a received signal and a transmit path including a transmit transducer for converting audio signals to electrical signals for transmission to a far-end user. An acoustic echo canceller is communicatively coupled between the receive path and the transmit path and includes a subtractor circuit connected ser...

Disclosed are a mobile communication terminal provided with a hands-free function and a controlling method thereof comprising the steps of: setting a hands-free function of a mobile communication terminal; certifying whether an originating call command or a calling request message are received; searching information of a calling party inputted by a user's voice or an arbitrary originating party's information from a mounted telephone directory; and guiding the searched calling party's information...

A telecommunication device (10) includes a housing (14, 16) and a dual earpiece arrangement (26) associated with the housing. The dual earpiece arrangement (26) includes a handsfree transducer (28) that generates dispatch-level audio output in a handsfree operating mode of the telecommunication device, and a private-mode transducer (38) that generates private-level audio output in a private operating mode of the telecommunication device. In particular, the device (10) includes a cantilevered ben...

A handset comprising a sealed unit receiver and a loudspeaker, first apparatus for providing sound from the receiver to the ear of a user when the ear of the user is sealed to the handset, and second apparatus for providing sound from both the receiver and from the loudspeaker to the ear of the user when the ear of the user is only partly sealed to the handset.

An integrated mobile-phone handsfree kit combined with an existing vehicular stereo system utilizes the high power and high performance audio output characteristics to provide drivers with a safe, comfortable and high quality conversation environment in vehicle. The invention comprises an existing stereo equipment with loudspeakers, and an electric power module connected to the stereo equipment to share the same power supply. The stereo equipment has a sound output wire and an electric power sup...

A wireless terminal for personal communication systems is provided with selective handsfree or handset receive mode of operation utilizing a single transducer. The transducer is mounted within a specially designed enclosure having front and back chambers each with strategically located acoustic ports for shaping the frequency response and providing good quality audio in each mode. Electronic equalization may be employed to further adjust the amplifier gain and shape the frequency response for du...

A speakerphone having echo suppression is provided. The speakerphone has an audio control system comprising a transmit path, a receive path, a pair of rectifiers for producing rectified signals indicative of the strength of the signals present on the receive path and the transmit path, respectively, and an analog-to-digital converter for generating digital samples of the rectified signals for further processing. The audio control system further includes a general use microprocessor. Samples of t...

A key telephone system is disclosed comprising microphone and loudspeaker equipped key telephone sets in which intercom calls are received through the microphone and loudspeaker. Additionally, the microphone and speakers may be used for central office calls. When so used, brief intercom calls can be allowed to break in, automatically placing the central office call on hold.